The present invention relates generally to dynamoelectric machines. More specifically, this invention relates to the cooling of a rectifier and/or stator of dynamoelectric machines.
A common application of a dynamoelectric machine is to utilize it as an alternator in a motor vehicle. The alternator produces three-phase alternating current which is rectified into a direct current. This energy can be stored in a battery of the motor vehicle or used by the electrical circuitry of the vehicle which utilizes direct current (DC) voltage. The three-phase alternating current is rectified to direct current by means of a rectifier bridge having a plurality of diodes, commonly either 6 diodes for a normal three-phase alternator or 12 diodes for a parallel three-phase alternator. Half of the diodes (either 3 or 6) are positive diodes. Each positive diode is connected between a phase terminal of a stator winding of the alternator and a positive terminal of the alternator. The positive terminal is connected to the battery and the electrical circuitry of the vehicle. The remaining diodes are negative diodes and are each connected between a phase terminal of the stator winding and electrical ground of the vehicle.
The diodes can experience current in excess of 200 amps. This level of current creates a significant amount of heat that must be dissipated to preserve alternator function and reliability. Heat is typically dissipated via carrier plates that the diodes are embedded in. The carrier plates act as heat sinks and may include fins which are exposed to cooling air. With this configuration, heat from the diodes is transferred to the carrier plates and to the fins where the heat is radiated to the atmosphere.
Current rectifier and heat sink configurations do not provide sufficient cooling to maintain component temperatures at a safe, reliable level in alternators where an output current exceeds 200 amps. The art would well receive an improved rectifier and heat sink configuration to sufficiently dissipate heat from the components in high current alternators.